Firebase Auth errorFirebase Auth: auth/user-mismatch

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Why the accounts don’t match, and the fix

1. 01

   The user picked another Google account

   “The supplied credentials do not correspond to the previously signed in user.” Firebase JS SDK, Firebase JS SDK auth errors (user-mismatch)

   The popup shows every Google account in the browser, and the user chose a different one. Pre-select the current one with login_hint and say which account to use.

   import { getAuth, GoogleAuthProvider, reauthenticateWithPopup } from 'firebase/auth';
   
   const auth = getAuth();
   const provider = new GoogleAuthProvider();
   provider.setCustomParameters({ login_hint: auth.currentUser.email });
   await reauthenticateWithPopup(auth.currentUser, provider);

2. 02

   The reauth form takes a typed email

   “When this happens, re-authenticate the user by getting new sign-in credentials from the user and passing the credentials to reauthenticateWithCredential.” Firebase, Manage users (re-authenticate a user)

   A form that asks for both email and password lets the user type another account. Fill the email from currentUser.email, lock the field, and ask only for the password.

   import { EmailAuthProvider, reauthenticateWithCredential } from 'firebase/auth';
   
   const user = auth.currentUser;
   const credential = EmailAuthProvider.credential(user.email, password);
   await reauthenticateWithCredential(user, credential);

3. 03

   The account was deleted

   If the user was deleted in the console or by an admin script, the SDK turns the user-not-found result into this same code. Sign the user out and send them to sign-up or sign-in.

4. 04

   The sensitive action ran anyway

   Also check: the failed reauthentication leaves the old session in place. Run the delete, email change or password change only after reauthentication succeeds.

Checked against the vendor’s docs on November 9, 2026: Firebase docs: Manage users (re-authenticate a user); Firebase JS SDK source: auth errors; Firebase JS SDK source: reauthenticate.ts.

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Related: Firebase auth/requires-recent-login · Firebase auth/multi-factor-auth-required · Firebase auth/credential-already-in-use · Firebase user-token-expired